Everything Everywhere Daily: History, Science, Geography & More - Geothermal Energy

Starting point is 00:00:00 Wherever you happen to be listening right now, at some level beneath your feet, the rocks in the earth reach a temperature hot enough to boil water and create steam. And with steam, you can turn a turbine and create electricity. If everywhere on earth is just a few kilometers away from tapping into this source of energy, why don't we use this everywhere? Learn more about geothermal energy, its uses, and its limits on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? Throughline is a podcast that takes you back. back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the Thuline podcast from NPR. Geothermal energy is pretty simple. Geothermal means Earth and Thermal means heat.

Starting point is 00:01:07 Geothermal is just tapping into the heat deep inside the Earth. Before I get into the details of how we can get usable energy from the Earth's heat, I should explain why the earth is so hot below the surface. There are two sources of heat inside the earth. The first comes from the primordial heat from when the earth was first formed. When all the loose rocks collided with each other about four billion years ago, it created an enormous amount of heat from friction. As more and more rocks amalgamated to form the planet,

Starting point is 00:01:34 all of the heat became trapped. As rocks aren't a very good conductor of heat, much of that original heat is still there. Primordial heat contributes to about half the heat inside the earth. The other source of heat comes from radioactive decay. As radioactive elements naturally decay, they release heat, which, like primordial heat, is for the most part trapped. The natural radioactive elements, which are responsible for this heat, are mostly uranium, thorium, and potassium. Over time, the interior of the Earth is gradually cooling down, but it's a very slow process.

Starting point is 00:02:06 The radioactive isotopes eventually get used up, and heat is lost via volcanoes and other fissures in the Earth's crust. That being said, we are a little, long, long way from that ever happening. Estimates I have read is that there is enough heat in just the top 10 kilometers of the Earth's crust to provide all of the energy for humanity for over 200 million years. The Earth's interior has three major parts, the core, the mantle, and the crust. Humans live on the crust, and we have never drilled beyond the crust. There's a good chance that we never even will.

Starting point is 00:02:41 If you remember back to my episode on the world's deepest hole, the Kola Super Deep borehole, it was drilled by the Soviet Union and it was just an effort to see how deep they could drill. It took them 17 years to reach an ultimate depth of 12,262 meters or 40,230 feet. The thickness of the Earth's crust can vary dramatically depending on where on the Earth you are. At its thickest, it can be about 80 kilometers, and at its thinnest, it's about one kilometer. geothermal heat has been used for thousands of years in the form of hot springs. If the crust is thin enough, or if there's a fault somewhere in the crust, hot water can rise to the surface creating a hot spring.

Starting point is 00:03:20 The oldest known hot spring that humans tapped into dates back to the 3rd century BC at the Waching Chai Palace in China. The Romans harness geothermal heat at their baths in Bath, England, and outside the town of Merida in Spain. In the 20th century, geothermal heating began to be used for individual buildings and greenhouses in places like Iceland and Idaho. As electrification took off in the early 20th century, some invented people realize that this heat coming from the ground

Starting point is 00:03:46 could be used to spin a turbine to produce electricity. In 1904, Piero Conti created a geothermal turbine at the Lardarello Springs in Tuscany, Italy. This first geothermal electricity could power four light bulbs. In 2011, it was the locations of the world's first industrial-scale geothermal electric plant. And today, Lardarello produces 10% of all of the geothermal. thermal electricity in the world. Using the Earth's heat to create electricity wasn't something that really caught on right away. In 1958, a commercial facility was built in New Zealand, and in 1960, one was built in California. The simplest type of geothermal power is called a dry

Starting point is 00:04:23 steam system. In this type of system, steam is heated directly from the ground and sent through a turbine, and then once cooled, the water would be pumped back into the ground. These were the first type of geothermal plants, and they're the most popular today where steam is easily accessible. Another type is a flash steam generator. In this, hot water is pumped out of the ground, but it's not steam. It's then pumped into a low-pressure container, which causes it to boil, and then the steam is run through a turbine. A third type is called a binary cycle generator. These can use water temperatures that are much lower. The hot water runs through a heat exchange, which heats up another fluid with a boiling point that's much lower than water. The second

Starting point is 00:05:03 fluid then turns to a vapor and is run through a turbine. As of today, there are about 11 gigawatts of electricity produced by geothermal power worldwide. The world's largest producer is the United States, followed by Indonesia and the Philippines. The world's largest geothermal facility is in the geysers in California, which is located about 72 miles north of San Francisco. The countries which get the highest percentage of their electricity from geothermal are Iceland, El Salvador, Costa Rica, Kenya, and the Philippines, which all get over 15%. What all the countries I just mentioned have in common is that they have geothermal facilities located in places where the Earth's crust is thin, and heat is easily accessible. Most are located in places like the Ring of Fire around the Pacific,

Starting point is 00:05:48 the Great Rift Valley in Africa, or between two tectonic plates such as in Iceland. Globally, the total amount of electricity provided by geothermal is only 1%. The real question is, If the earth's heat is located right beneath our feet, and it requires no fuel, and it's clean and available 24-7, why don't we use geothermal power for everything? In theory, and I do mean in theory, we could. However, it would be really expensive. The current geothermal power plants are located where it's cheap and easy to access the air seat. But as you get away from those places, getting to that heat requires drilling deeper down. and more importantly, it almost always requires drilling through bedrock. Most oil and gas drilling is done through sedimentary rock, which is relatively easy to drill through.

Starting point is 00:06:36 Igneous rock, like basalt or granite, is much harder and much more difficult to drill through. Moreover, the deeper you drill, regardless of what you're drilling through, the more expensive it gets. To get to a point where temperatures are enough to boil water, you need to drill down to about four kilometers or two and a half miles on average everywhere on earth. Moreover, it isn't just a matter of getting to the heat. You also need groundwater. There are systems known as enhanced geothermal systems which will pump water into fractures within the rock. But this has its own risks, including the possibility of creating earthquakes, if the pressure from the injected water dislodges a pre-existing fault.

Starting point is 00:07:12 There is some good news on the horizon in terms of lowering the cost of drilling. There have been developments in the use of high-powered microwaves to blast through bedrock. The system in theory could drill down to 12-mile, or 19 kilometers where you could have super critically heated steam. Tests are still being run, but if it turns out to be feasible, it could dramatically reduce the cost of drilling geothermal boreholes by tenfold. While geothermal electrical generation may get most of the attention, it is not the only or even necessarily the best method of harnessing the heat of the earth.

Starting point is 00:07:45 Another much simpler use is for heating and cooling. Geothermal heating and cooling is something that can be set up for almost any building, anywhere in the world. It doesn't require drilling deep boreholes. There are several different methods that can be used, but they all involve digging a hole or ditch near the building and then running pipe in the hole, usually in a looping pattern to increase the distance and then burying the pipe. Depending upon the depth of the pipe and the location of the installation, the temperature below ground will be cooler than the outside air in the summer and warmer in the winter. At a minimum, you could just pump water through it to exchange the heat. However, there's a much more efficient system known as a

Starting point is 00:08:21 ground-sourced heat pump. A heat pump works on the same principle as a refrigerator, and instead of a single heat exchanger, you would have two of them, which can be reversed, depending on if you want to heat or cool your house. Heat pumps are much more efficient than alternative heating and cooling systems, and they are made even more efficient by having a higher heat difference, which is possible by running it through the ground. Ground-sourced heat pumps can save 30 to 70% in heating bills and 20 to 50% in cooling bills. A ground-sourced heat pump is probably one of the simplest and cheapest ways to harness the earth's heat to provide energy. Geothermal heating and cooling systems have been used in greenhouses, and they work especially well

Starting point is 00:08:59 in cold climates. With the geothermal heating system, greenhouses can grow citrus fruits even when there's snow outside. Currently, and at least for the foreseeable future, geothermal electrical generation will probably be limited to areas that are close to fault lines or volcanoes. While there are still a lot more places where it could be implemented, it probably isn't something that will be adopted outside of fault zones until drilling technology dramatically improves. Crown-sourced heat pumps and geothermal heating are something that can be put into practice almost everywhere right now. And if I was building a new home today, it's definitely something that I would install.

Starting point is 00:09:37 Everything Everywhere Daily is an Airwave Media podcast. The executive producer is Darcy Adams. The associate producers are Thorpe Thompson and Peter Bennett. Today's review comes from listener 10-second Forward over at Apple Podcasts in the United States. They write, extremely informative. So good. I love being exposed to things I probably wouldn't have come across otherwise. Short enough to be an easy listen, long enough to provide good context and the details of the topic of the day. It's prompted me to look further into some of the issues.

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Everything Everywhere Daily: History, Science, Geography & More - Geothermal Energy

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